﻿/**
 * Copyright (c) 2011-2016, Mobangjack 莫帮杰 (mobangjack@foxmail.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace util
{
    class LinkedStack<T> : IStack<T>
    {
        private Node<T> peek;
        private int count;

        public LinkedStack()
        {
            peek = new Node<T>();
            count = 0;
        }

        public void Push(T item)
        {
            peek.data = item;
            Node<T> rear = new Node<T>();
            rear.front = peek;
            peek.rear = rear;
            peek = rear;
            count++;
        }

        public T Pop()
        {
            T tmp = peek.data;
            peek = peek.front;
            return tmp;
        }

        public T Peek()
        {
            return peek.data;
        }

        public int Count()
        {
            return count;
        }
    }
}
